Binding to View Model properties in Data Templates. The RootBinding Markup Extension

RootBindingExtension.cs

public class RootBindingExtension : IMarkupExtension<Binding>
{
    public string Path { get; set; }
    
    public Binding ProvideValue(IServiceProvider serviceProvider)
    {
        IRootObjectProvider rootProvider = (IRootObjectProvider) serviceProvider.GetService(typeof(IRootObjectProvider));

        var view = rootProvider.RootObject;
        var fe = view as FrameworkElement;

        if (fe == null)
        {
            throw new InvalidOperationException("Root element must have data context");
        }

        var binding = new Binding();
        binding.Path = new PropertyPath(this.Path);
        binding.Source = fe.DataContext;

        return binding;
    }
}

Usage.xaml

<Grid x:Name="LayoutRoot" Background="White">
    <ListBox ItemsSource="{Binding Names}">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal">
                    <TextBlock Text="{Binding}"/>
                    <Button Content="{current:RootBinding Path=ButtonContent}" Command="{current:RootBinding Path=MessageBoxCommand}"/>
                </StackPanel>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
</Grid>